The ACSYS Historical Ice Chart Archive presents historical sea-ice observations in the Arctic region between 30ºW and 70ºE in the form of digitized maps, stored as shape files. The earliest chart dates from 1553, and the most recent from December 2002. More recent charts are available electronically from the Norwegian Meteorological Institute (www.met.no).

Vessels sailing to the Arctic to explore or to hunt whales and seals made early sea-ice observations. Over the centuries, technological advances and commercial opportunities in the Arctic led to more frequent and regular sea-ice observations, with associated increasing accuracy. As sailing ships gave way to steam powered vessels, and with the advent of aircraft and satellites, regular mapping of sea ice conditions became an organized activity. From 1967 onwards, hand drawn weekly charts were produced, showing not only an ice edge, but also concentrations of sea ice within the ice pack. Since July 1997, improved technology allowed daily production of digital sea ice maps on workdays.

In an effort spanning many years, early observations from ship logbooks and other records were collected, translated as necessary, and plotted as hand-drawn maps. For more recent years, sea ice charts from various organized sources were collected. The total of over six thousand charts were placed on two CD-ROMs, and these can be viewed and analysed using geographical information system (GIS) software. The data set is complemented by less detailed ‘quick-look’ versions of all maps.

This report provides background information regarding the data and its collection. Prospective users should consider the uncertainties related to the ice-edge definition, and to the difficulty of navigating in remote areas prior to the satellite era.